Reason is a language that looks and reads like Javascript, writes like Javascript, and even interops nicely with Javascript. But it is in fact a new syntax for OCaml, a powerful statically typed functional programming language.
The syntax makes ReasonML easy to start playing with, but unless you already know a typed functional language, you will soon run into stumbling blocks because of unfamiliarity with static types and functional programming.
Fear not! Work through these exercises and learn all the basics - defining and using functions, understanding recursion, lists, list operations, variants, and all the way till mutable variables. They will give you a great foundation to start mastering this beautiful language.
These exercises are originally from a workshop organized by Jane Street for teaching OCaml to programmers who work in other languages and who do not necessarily have experience with functional languages. Link to the original repo. We adapted the tutorials and exercise code to the Reason syntax and toolchain.
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Setup your editor. We recommend
VSCodealong with the vscode-reasonml extension. If you prefer a different editor check the instructions for other supported editors -
Clone the repository and open the project
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Run
npm install
The exercises are numerically ordered and can be found in the src/exercises directory.
It is recommended to have two shells open.
Run npm run start in the first shell. It will re-compile the project on every save. This is usefull to catch compilation errors.
Run npm run test:watch in the second shell. It will use Jest to run all the tests. Note that tests run only when the compilation is successfull. If not - we are covered by the first shell.
Tip: when Jest is running, pres p and enter a fragment of a filename you are working on. It will run only the tests from the matching file.